I adopted a Schnauzer from the SPCA a couple of months ago. He's 1.5 years old and not yet neutered (He will be in about a week). I think he was not really taken care of when growing and he was probably not very well socialized.
He is an extremely good dog. We have no issues with him when he is in the house, we taught him the sit, stay, come, and lie commands and he would only bark if a stranger comes in the house and it would normally stop soon after.
However, his walks can be a bit challenging. He gets very anxious/hyper when he knows he is going outside. As soon as he steps out he starts barking like crazy!! He pulls (not too bad though and usually only during the first minutes of the walk) but he would bark as soon as he sees any other dog, cat, bird, squirrel or human. He has a very pitchy bark and sounds like I am killing him!
Also, when he is out (either during the walk or when he is in the backyard), he completely loses his concentration and would not respond to any of the commands he normally performs in the house.
I'm not really sure how to deal with this, I've tried teaching him the quiet command but I haven't been successful. I really don't want to use the barking collars on him and I'm thinking of training classes.
Anyone there with similar issues and advice?? Thanks a lot.

I'd definitely recommend some training classes. Not only are they are a great way to learn some new tricks and focus exercises, it's also a great way to bond with your dog

In regards to his reactions to other dogs, etc during walks - you need build up a threshold for this. The minute he starts to react, it's too late and any learning opportunity is over. It may mean that the minute you notice another dog, you immediately turn around and walk in the opposite direction, praising him the entire time with lots of high value treats. If it's a house that has a dog in the back that is known to bark, maybe cross over to the other side of the street. Anytime your puppers looks at you, give him a treat. If you know people with dogs, it may even help to set up situations for practicing

Livia has this issue right now and I can tell you it has gotten a lot better over the past few months, but it takes a lot of work and patience. We also invested in a halti which was recommended as you can refocus their head away from the distraction - but it isn't working for us! She pulls and lunges so much with it that I'm concerned about neck safety. We're moving to a harness as soon as it comes in

It may mean that the minute you notice another dog, you immediately turn around and walk in the opposite direction, praising him the entire time with lots of high value treats.

This is exactly what we do but at the same time I want him to be able to interact with other dogs.

We are on our third type of leash now...we also bought the Halti and it did work for Rocoto in terms of limiting his barking (a bit the pulling too) but I think it is a bit tough on him and irritates his face...every time we use it he starts scratching his face like crazy so we decided to stop using it.
Now we are using the Lupi which works great for the pulling but not so good for the barking!

This is exactly what we do but at the same time I want him to be able to interact with other dogs.

I understand you wanting him to interact with other dogs so I suggest obedience classes, puppy play dates, etc. Leash meetings isn't a fun introduction for most dogs anyway, and especially if it's stressful/fearful for yours.